1. Field of the Invention
This invention relates to a transmission and relates particularly to an apparatus with the multi-stage power shifting means applied to a machine tool.
2. Description of the Related Art
A typical power transmission device on a machine tool has different designs for the power output, such as a single high torque design, a dual medium high torque design and a dual medium low torque design. The device with the dual shifting motion only provides two modes of output torque for use, so the single device cannot satisfy the need, and multiple alternate machine tools with different power output values are needed during a processing step. This alternate operation may decrease the processing efficiency of the machine tool. The processing mode of the machine tool is also restricted because of lack of insufficient variation of the power transmission. Furthermore, the gear construction of the device needs an increased bulk for increasing the gear reduction ratio, and this brings the device a quite big bulk. Therefore, an improvement is still needed.